We did this for our house built in 68. Obviously it depends on the architecture but we where able to place the central unit beneath the roof. All rooms on the

We did this for our house built in 68. Obviously it depends on the architecture but we where able to place the central unit beneath the roof. All rooms on the first floor are connected through the roof space. A central column runs through the first floor and goes to the corridor on the ground floor. From there we where able to connect all rooms. The floor lost 15 cm height but it has 250 cm so it did not matter much. If you cannot do it you can run the pipes on the exterior walls and insulate them with ,20 cm Styropor.